Erosion behaviour of suspension plasma sprayed thermal barrier coatings
2018 (English)Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE credits
Student thesisAlternative title
Erosionsbeteende hos plasmasprutade termiska barriärbeläggningar (Swedish)
Abstract [en]
Thermal barrier coatings (TBCs) are applied on the surface of hot parts of gas turbine engines to increase the turbine efficiency by providing thermal insulation and also to protect the engine parts from the harsh environment. To maximize these benefits, the TBC must remain intact to the underlying metallic gas turbine components through the life of the gas turbine engines. Typical degradation of TBCs can be attributed to bond coat oxidation, thermal stress etc. In addition to this, erosion can also lead to partial or complete removal of the TBCs especially when the engine operates under erosive environment such as flying over desert area, near active volcanic or offshore ocean environment. Therefore, erosion is also acknowl-edged as a significant life-limiting factor for TBCs. Suspension plasma spray (SPS) is a rela-tively new technique capable of producing coatings with lamellar/vertically cracked and co-lumnar microstructures. Moreover, SPS is a cheaper process compared with Electron Beam Physical Vapor Deposition (EB-PVD) which is a well-known commercial technique to produce columnar TBCs. This work aims to study the effect of microstructure produced by SPS on the erosion performance of TBCs. Six different suspensions of 8 wt. % Yttria Stabilized Zirconia (YSZ) ceramic powder with distinct suspension characteristics such as solid load, solvent type and particle size distribution were used to spray six different TBCs using an identical bond coat and substrate. The as-sprayed TBCs were subjected to an air jet erosion test at room temperature, and their erosion resistance was compared. It was found that the total porosity content in the coating was the most predominant factor influencing the erosion performance of the coatings. Moreover, vertically cracked coatings resulted in low total po-rosity which in turn lead to high erosion resistance. This result was also supported by one of the columnar coatings which had the lowest porosity and highest erosion resistance as com-pared to other columnar coatings. Therefore, it is recommended to produce a columnar coating with lower porosity content for SPS TBCs.
Place, publisher, year, edition, pages
2018. , p. 30
Keywords [en]
Erosion, thermal spray, suspension plasma spray, thermal barrier coatings, co-lumnar microstructure, lamellar microstructure
National Category
Mechanical Engineering
Identifiers
URN: urn:nbn:se:hv:diva-12987Local ID: EXP800OAI: oai:DiVA.org:hv-12987DiVA, id: diva2:1253597
Subject / course
Mechanical engineering
Educational program
Produktionsteknik
Supervisors
Examiners
2018-10-122018-10-052018-10-12Bibliographically approved